In manufacturing a semiconductor device, various processings such as, for example, film forming and etching, are performed on a substrate to be processed so as to form a fine pattern. Such a pattern formed on a substrate to be processed tends to be finer and finer and thus, a control of an etching amount in the order of several nm or less is requested.
An atomic layer etching (ALE) method receives attention as a technology for controlling such an etching amount. The ALE method is a technology of etching a substrate to be processed to an atomic layer level by causing an etchant gas to be adsorbed on the substrate to be processed, and then, generating plasma of an inert gas such as, for example, Ar gas. For example, Patent Document 1 discloses a technology based on such an ALE method.